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Updated on: 19 Mar 2015, 05:38
Originally posted by ritumaheshwari02 on 29 Nov 2012, 09:56.
Last edited by Bunuel on 19 Mar 2015, 05:38, edited 2 times in total.
Last edited by Bunuel on 19 Mar 2015, 05:38, edited 2 times in total.
Edited the tags.
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D
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Difficulty:
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If the ratio x: y:z is 3:5:7, what is the value of z?
(1) The average (arithmetic mean) of x, y, and z is 25.
(2) The value of x is 15.
(1) The average (arithmetic mean) of x, y, and z is 25.
(2) The value of x is 15.
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
Data Sufficiency Forum
Data Sufficiency Forum
29 Nov 2012, 10:01
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ritumaheshwari02
x:y:z = 3:5:7
means x=3k, y=5k, z=7k where k is the common value in all the three numbers.
STAT1
(x+y+z)/3 = 25
x+y+z = 75
=> 3k + 5k+ 7k = 75
15k = 75
k = 5
z = 7k = 35
SUFFICIENT
STAT2
x= 15
=> 3k = 15
=> k =5
=> z = 7k = 7*5 = 35
SUFFICIENT
Answer will be D
Hope it helps!
18 Mar 2015, 20:04
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Hi All,
With the given ratio, we know that X is a multiple of 3, Y is an equivalent multiple of 5 and Z is an equivalent multiple of 7. By extension, the sum of those 3 terms is a multiple of 15
For example, we could have X=3, Y=5 and Z=7 (and the sum = 15) or X=6, Y=10, Z=14 (and the sum = 30)
We're asked for the value of Z .
Fact 1: The average (arithmetic mean) of x, y, and z is 25.
Since the average of the 3 terms is 25, the SUM of the three terms is 75.
75 is a 5 times 15, so we can calculate the value of all 3 variables:
X = 3(5) = 15
Y = 5(5) = 25
Z = 7(5) = 35
Fact 1 is SUFFICIENT
Fact 2: The value of x is 15.
Since X = 15, we can figure out the "multiple of 3" that we're dealing with. 3(5) = 15, so we have to multiply the Y and the Z by 5 also.
Y = 5(5) = 25
Z = 7(5) = 35
Fact 2 is SUFFICIENT
Final Answer:
GMAT assassins aren't born, they're made,
Rich
With the given ratio, we know that X is a multiple of 3, Y is an equivalent multiple of 5 and Z is an equivalent multiple of 7. By extension, the sum of those 3 terms is a multiple of 15
For example, we could have X=3, Y=5 and Z=7 (and the sum = 15) or X=6, Y=10, Z=14 (and the sum = 30)
We're asked for the value of Z .
Fact 1: The average (arithmetic mean) of x, y, and z is 25.
Since the average of the 3 terms is 25, the SUM of the three terms is 75.
75 is a 5 times 15, so we can calculate the value of all 3 variables:
X = 3(5) = 15
Y = 5(5) = 25
Z = 7(5) = 35
Fact 1 is SUFFICIENT
Fact 2: The value of x is 15.
Since X = 15, we can figure out the "multiple of 3" that we're dealing with. 3(5) = 15, so we have to multiply the Y and the Z by 5 also.
Y = 5(5) = 25
Z = 7(5) = 35
Fact 2 is SUFFICIENT
Final Answer:
GMAT assassins aren't born, they're made,
Rich
